Deploying a Real Application Cluster on Oracle Cloud Infrastructure | RAC on OCI | K21 Academy

[@bharathmc7964]

Thanks for the demo. How does application connect to RAC database in ideal scenario ? In this demo we used 2 node instance RAC. When application connects to this DB, does it connect to individual instances or there is a single load balancer IP (which I am assuming SCAN) ?

[@K21Academy]

Hi there! In an ideal scenario with a two-node instance RAC (Real Application Cluster) setup, the application typically connects to the RAC database using a Single Client Access Name (SCAN). The SCAN is a virtual hostname that represents the entire cluster rather than individual instances. It acts as a single entry point for client connections, providing a consistent address for connecting to the RAC database regardless of the underlying nodes or instances. The SCAN IP address is associated with multiple virtual IP addresses (VIPs) that are assigned to the individual nodes in the cluster. When an application connects to the RAC database using the SCAN, the connection request is routed to one of the available VIPs associated with the SCAN. The VIP serves as a load balancer, distributing the incoming connections across the available instances in the cluster. This load balancing mechanism ensures that client connections are distributed evenly across the nodes, providing high availability and scalability. If one of the nodes or instances becomes unavailable, the VIP associated with that node is automatically reassigned to one of the remaining available nodes, ensuring continuous access to the database without interruption. I hope this helps!

[@eswar6311]

Thank Atul

[@K21Academy]

Thanks, keep supporting!